Motorola M68HC08 manual Introduction

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

Introduction

Once using the semiconductor components, it is opened to replace classical universal and DC-motors with maintenance-free electrically commutated BLDC motors. This brings many advantages of BLDC motors when the system costs could be maintained equivalent.

The advantages of BLDC motor versus universal and DC-motors are:

•high efficiency

•reliability (no brushes)

•low noise

•easy to drive features

To control the BLDC motor, the rotor position must be known at certain angles in order to align the applied voltage with the back-EMF, which is induced in the stator winding due to the movement of the permanent magnets on the rotor.

Although some BLDC drives uses sensors for position sensing, there is a trend to use sensorless control. The position is then evaluated from voltage or current going to the motor. One of the sensorless technique is sensorless BLDC control with back-EMF (electromotive force) zero-crossing sensing.

The advantages of this control are:

•Save cost of the position sensors & wiring

•Can be used where there is impossibility or expansive to make additional connections between position sensors and the control unit

•Low cost system (medium demand for control MCU power)

Designer Reference Manual		DRM028 — Rev 0
14	Introduction	MOTOROLA
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